This invention relates generally to methods for monitoring a semiconductor array production process and the arrays produced thereby, and more particularly to methods particularly suitable for monitoring and adjusting a manufacturing process for detector arrays that, while also more generally useful, is particularly suitable for monitoring production of flat panel x-ray detectors.
The performance of pixilated flat panel x-ray detectors (FP-XRD) is influenced by many different production parameters. Variations in performance due to film quality can appear spatially across a single panel, from panel-to-panel, and from lot-to-lot. Measurement of the amount of process variation is useful in controlling final performance variation during production of imaging panels, as is identifying the influence of the process on final device performance. If production yield drops, being able to quickly identify and improve the process step leading to the degradation would help reverse the drop in production yield.
At least one known procedure for controlling variability uses ex-situ monitoring of individual processes. For example, if the resistivity of a layer influences final performance, test films are grown on blank substrates and measured. Periodic growth of test films is used to monitor the quality of the process. However, ex-situ tests do not take into account interactions between process steps. For example, a later step may degrade the performance of a layer deposited in a previous step. At least one other known method of diagnosing problems includes fabricating a set of complete detectors in which a single or multiple process parameters are changed for each detector. The resulting performance of the detectors is then measured, and the sensitivity to process parameters determined. However, this method is inefficient in that it requires fabrication of a complete detector for each variation to be tested. Yet another known method includes fabricating individual test devices in a periphery of the panel, outside the active detection area. However, this approach reasonably measures only a small number of devices and does not provide information about spatial variations across the active area of the panel.